Nitrogen compounds, reduction with aluminum hydride

Piperideines unsubstituted at the nitrogen atom may be prepared from the corresponding pyridine compounds by partial reduction with sodium and boiling alcohols (the Ladenburg reduction), by electrolytic reduction, or, preferably, by reduction with aluminum hydride. l-Alkyl-3-piperideines are prepared by reduction of quaternary pyridinium salts with formic acid (the Lukes reduction) or with complex hydrides. 

The stoichiometry determines the ratios of lithium aluminum hydride to other compounds to be reduced. Esters or tertiary amides treated with one hydride equivalent (one fourth of a molecule) of lithium aluminum hydride are reduced to the stage of aldehydes (or their nitrogen analogs). In order to reduce an ester to the corresponding alcohol, two hydride equivalents, i.e. 0.5 mol of lithium aluminum hydride, is needed since, after the reduction of the carbonyl, hydrogenolysis requires one more hydride equivalent. 

The stoichiometry of lithium aluminum hydride reductions with other compounds such as nitriles, epoxides, sulfur- and nitrogen-containing com-... 

Miscellaneous Compounds. A saturated spirocychc pyrrohdine serves as the nucleus for a diamine that has been described as a hypohpemic agent. Treatment of the carbanion of the substituted cylcohexane carboxyhc ester (20-1) with methyl bromoacetate leads to the alkylation and formation of the diester (20-2). Saponification of the ester groups followed by reaction with acetic anhydride leads to ring closure of the succinic anhydride (20-3). Condensation with ammonia leads to the succinimide (20-4). The side chain is then added by alkylation of the anion on nitrogen with l-bromo-4-dimethylaminobutane (20-5). Reaction of this last intermediate with lithium aluminum hydride leads to the reduction of the carbonyl groups to methylene. This affords the pyrrolidine (20-6) atiprimod [22]. 

Excellent procedures are available for the preparation of primary, secondary, and tertiary amines by the reduction of a variety of nitrogen compounds. Primary amines can be obtained by hydrogenation or by lithium aluminum hydride reduction of nitro compounds, azides, oximes, imines, nitriles, or unsubstituted amides [all possible with H2 over a metal catalyst (Pt or Ni) or with LiAlH4] ... 

As shown by Schlesinger et treatment of an ethereal solution of aluminum chloride with excess lithium aluminum hydride leads to the formation of aluminum hydride which may be used in situ in reductions of a variety of nitrogen compounds.74,76 In these reductions, aluminum hydride shows a similar reductive ability as lithium aluminum hydride. 

Hydrolysis of 4,5-dicyanoimidazole yields 4-amino-5-imidazole-car-boxamide which is converted by hypobromite into 4-amino-5-imidazole carbonitrile.444 Hydrolysis of the dicyano compound with aqueous alkali yields the corresponding 4,5-dicarboxylic acid.156 Reduction of the dicyanide with lithium aluminum hydride occurs with greater ease when the imino nitrogen carries a methyl substituent.156... 

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